1. Field of the Invention
The present invention relates generally to the field of floating islands, and more specifically, to floating island modules comprised of post-consumer carpet fiber matrix.
2. Description of the Related Art
Manmade floating islands are useful for a wide range of applications including wastewater treatment, wildlife habitat, and waterscape beautification. Porous and permeable floating islands that biomimic natural floating islands are particularly useful because they can provide a combination of benefits, which include providing an internal growth substrate for natural water-purifying microbes, habitat for insects having value as fish food, nesting cover for fish and birds, growth areas for the roots of hydroponic plants, and environmentally-friendly wave attenuation and shoreline protection.
Floating Island International, LLC (FII) of Shepherd, Mont. has developed an extensive range of intellectual property and commercial products related to floating islands that utilize the concepts of porosity, permeability, large internal surface areas for microbial colonization, and internal buoyancy. A key component of many of these products is a mat of nonwoven polymer fibers that forms the body of the floating islands and promotes plant root growth and/or microbial biofilm colonization. Several forms of fiber matting have been used successfully for various floating island products. Prior-art examples of different types of polymer fiber matting include compressed fibers contained in a permeable net bag, compressed fibers bonded together with a binder to form a matrix material, and a hollow fiber-matrix box filled with compressed unbonded fibers.
U.S. patent application Ser. No. 11/569,491 (Kania et al.) describes the use of one or more layers of water-permeable mesh material comprising polyester fibers as a substrate for beneficial microbes and plant roots, which acts as a biological filter to remove water-borne contaminants, including excess nutrients. Various means of buoyancy, including buoyant nodules and injected, expandable foam, are also described.
U.S. Pat. No. 7,555,866 (Kania et al.) describes a floating island specialized for waterfowl nesting and comprising scrap pieces or layers of polyester mesh material.
New Zealand Patent No. NZ 581425 (Kania et al.) describes a floating streambed comprising permeable matrix, wherein the permeable matrix may be comprised of nonwoven polymer fibers, nonwoven polymer fibers comprised of polyester, or nonwoven polymer fibers comprised of recycled scrap carpet fibers. The fibers are intertwined to form a blanket approximately 1¾ inch thick, and a latex binder is sprayed onto the blanket and cured by baking. Multiple layers of matrix are stacked and attached to form blocks of any desired thickness. Buoyancy is achieved by injecting uncured polyurethane resin that expands in place within the matrix during the curing process.
International Patent Application No. PCT/US09/037,745 (Kania et al.) describes the use of “fiber wool” as an internal filler material for floating island modules, wherein the fiber wool may be composed of either natural or synthetic materials or a combination of both. Specifically mentioned synthetic materials include polyester, polypropylene, and polyethylene. Injected expandable foam is used as a means of buoyancy.
All of the embodiments described above have disadvantages that are overcome by the present invention. In the embodiments that utilize nonwoven polyester matrix, the cost of the matrix is relatively high. In the embodiments that describe the use of fiber wool, the fiber wool filler material has a much lower cost than the nonwoven matrix but has much less tensile strength and structural integrity than nonwoven matrix. In the embodiments that describe injected foam or inserted floats, the buoyant nodules produce localized zones within the interior of the floating islands that have reduced permeability, resulting in a structure having non-homogeneous permeability and buoyancy characteristics that may adversely affect water circulation to the beneficial microbes colonizing the interior regions of the matrix.
The present invention is a floating island module comprised of nonwoven polymer matrix comprised of recycled carpet fibers that are bonded together during manufacture with small droplets of optionally buoyant adhesive and encapsulated within permeable protective covers. The present invention results in a matrix-based module that retains the beneficial characteristics of the prior-art nonwoven polymer matrix modules related to permeability, porosity, and acceptable tensile strength, while significantly reducing the unit cost of materials and simultaneously providing the desired amount of buoyancy and eliminating the low-permeability zones of the injected foam of the prior art modules.
The present invention is particularly desirable for environmental remediation applications such as marine oil-spill cleanup, wherein the combination of fine, oil-attractive fibers and low cost provide an effective and disposable product.